//? 此题就是关于new
function foo(something){
    this.a = something
}

var obj1 = {
    foo: foo
}

var obj2 = {}

obj1.foo(2);
console.log(obj1.a); //? 2

obj1.foo.call(obj2, 3);
console.log(obj2.a); //? 3

console.log(obj1)
console.log(obj2)

var bar = new obj1.foo(4)
console.log(obj1.a); //? 2
console.log(bar.a); //? 4
console.log(bar)
